Structural joint connector

ABSTRACT

A structural joint for bearing a structural load is formed by a pair of wooden members fastened together by at least one metal connector plate. The connector plate is formed from a metal plate having a plurality of pairs of teeth punched therefrom. The teeth are punched from the plate so as to project in a direction substantially perpendicular to the plate. Each pair of teeth is struck so as to leave a corresponding longitudinally extending slot between the teeth. Each of the teeth has a knife edge portion that extends from the plate. This knife edge portion is thinner than the remaining portion of each tooth and has a sharp edge with a cross-sectional angle of less than 20°, preferably 8° to 12°, for facilitating penetration of each of the teeth into the wooden members to be secured together. These knife edge portions of the teeth are made by a metal forming process which serves to shape such portion of the teeth and simultaneously widen and elongate each tooth.

This is a division of application Ser. No. 71,551, filed Aug. 30, 1979,now U.S. Pat. No. 4,343,580.

BACKGROUND OF THE INVENTION

The present invention involves a metal connector plates forinterconnecting members such as the wooden members forming a structuraljoint. The invention also involves the method and apparatus for formingsuch connector plates. Typically, such connector plates are utilized forinterconnecting adjacent wooden members for forming a structural jointsuch as a roof or floor truss structure as shown in U.S. Pat. No.2,877,520 to Jureit.

When interconnecting such wooden members, the two members are arrangedso as to be butted together and a connector plate is either pressed orrolled into such abutting members. If a pressing action is used, theconnector plate is arranged so as to sit on top of the wooden membersand then a pressing force is applied. In the alternative action, theconnector plate is rolled into the wood such as shown in U.S Pat. No.3,479,920 to Sanford. While it has been common practice for severalyears to roll connector plates for forcing them into the wood, suchaction has lead to several deficiencies in the final product as comparedto the pressed connector plates. During the rolling action, there is atendency for the connector plate to slip until it is firmly secured tothe wood. Additionally, the rolling force applies both a forceperpendicular to the plate and a longitudinal force to the plate. Thislongitudinal force can and often did lead to bending of the teeth of theconnector plates until the teeth were firmly secured by a sufficientdepth in the wood. Such bending, typically referred to as a submariningeffect, was especially prevelant in those situations where the teeth metwith any significant resistance against penetration from the wood. Wheresuch a submarining effect becomes significant, the teeth do notpenetrate the wood as deeply as desired thereby reducing the effectivestrength of the structural joint.

Another problem that occurs when rolling the connector plates forforcing them into the wooden members occurs since the force of the largeroller that is typically utilized has a tendency to cause the connectorto conform to the shape of the roller. The curving of the plate meansthat the teeth when contacting the wood will be oriented at an inclinedangle instead of being perpendicular to the wood. This effect increasesthe tendency for bending or submarining of the teeth when they enter thewooden members. This problem has been long recognized in the prior artand in fact is discussed in the above noted Sanford patent, U.S. Pat.No. 3,479,920, which discloses a connector plate specially designed forroller presses.

The strength of the structural joint is typically measured with respectto the capability of the connector plate to resist withdrawal from thewooden members when subjected to longitudinal stress and the resistanceprovided by the connector plate against rotation of the wooden members.While conventional plates have had a high holding capability againstlongitudinal forces applied along the axis of the abutted woodenmembers, the holding capability against rotation of the wooden membershas been lower. In attempting to improve the resistance against rotationU.S. Pat. No. 3,951,033 to Moehlenpah discloses a connector plate havinga plurality of pairs of teeth. The connector plate is provided with afirst group of such pairs of teeth oriented in one direction and pairsof teeth oriented in a different direction. Hydro-Air Engineering, Inc.markets its P-T truss plates utilizing the designation of U.S. Pat. No.3,951,033. FIG. 8 illustrates a perspective view of a portion of aHydro-Air P-T plate.

The Hydro-Air connector plate, both as shown in the patent to Moehlenpahand the plate itself, has a plurality of pairs of teeth with each pairbeing cut from a single slot. Each tooth is twisted so as to have onesection that extends further forward than the remainder of the tooth.The thickness of each tooth is substantially constant and the forwardedge has a cross-sectional angle of approximately 45°. While notillustrated in the patent, in the Hydro-Air plate marketed under thepatent, each tooth is twisted so as to actually lean either to the rightor left, i.e., the teeth are not aligned with the slots such as shown inFIG. 8.

The twisting of the teeth so as to lean in one or the other direction isa common phenomenon that will occur when air cutting the teeth from themetal plate. Such an air cutting process is illustrated in U.S. Pat. No.3,685,336 to Black. While the patent to Black does show a typical aircutting process for cutting the teeth out of the plate, it does notillustrate the twisting of the nails that will typically inherentlyoccur. Such twisting of the nails which causes them to lean in one orthe other direction will lead to a further bending of the teeth in thesame direction as the connector plate is rolled into the wooden members.Such bending of the nails leads to a submarining effect which will oftenweaken the structural joint. In essence, such a submarining effect meansthat the teeth are not embedded in the wood to the fullest possibleextent but are bent over so as to be positioned relatively close to thesurface of the wood thus being more easily withdrawn when the woodenmembers are placed under load. The effective result of such submariningeffect on the strength of the joint will greatly vary in dependence uponthe type and nature of the wood used in forming the joint. Thus, forexample, in harder woods the problem is more significant.

In addition, the relatively blunt angle of the teeth of the Hydro-Airplate and as illustrated in the patent to Moehlenpah generates a greaterresistance to entry of the teeth into the wood. As previously discussedsuch resistance to entry causes a shifting of the plate and furtherbending of the teeth thereby increasing the submarining effect.

Furthermore, due to the blunt angle of the edges of the teethillustrated in the Moehlenpah patent and in the Hydro-Air plate, thereis a compressing action on the wood grain when such teeth are rolledinto the wooden members. Such compressing of the wood creates a tendencyfor the wood to collapse thereby creating a hollow space under the platearound the teeth and weakening the grip of the wood on the teeth and thestructural strength of the joint.

During such an air cutting operation in the production of the connectorplates, the space between the end walls of the punch and the inner endwalls of the die cavity has always been greater than the thickness ofthe metal so that a free space remains after the teeth have been struckfrom the metal and pushed into the cavity. If the space was not largerthan the thickness of the metal then friction would be generated as themetal was pressed against the inner end walls of the cavity therebygenerating heat which could lead to a change of the shape of the die byexpansion and contraction, warp the die or also possibly break the dieor punch. Thus, the prior art has avoided such problems by allowingextra space in the area of the end walls of the punch and die cavity.

Another patent illustrating a connector plate having a plurality ofpairs of teeth with a first group of such pairs oriented in onedirection and the remainder of the teeth oriented in the other directionalthough the slots extend in a longitudinal direction is U.S. Pat. No.3,603,197 to Wood. The patent to Wood illustrates a connector platehaving a plurality of pairs of teeth that are substantially similar andin many ways identical to the teeth and connector plate illustrated inthe above-noted patent to Moehlenpah. Other patents showing pairs orteeth cut from a connector plate with the teeth oriented in differentdirections are U.S. Pat. Nos. 3,094,748; 3,104,429; and 3,221,043, allto Sanford.

The connector plates are made by passing a metal sheet material inincremental steps between a set of punch and corresponding dies. Thesheet material is stricken by the punches which cut the teeth andproceed to enter into the cavities of the dies so as to produce theteeth. Such procedures and the apparatus for carrying out suchprocedures are illustrated in U.S. Pat. Nos. 3,314,271 to Otis and3,685,336 to Black. Both of these patents are hereby incorporated byreference. As previously discussed, the patent to Black illustrates anair cutting procedure for producing a pair of teeth struck from eachslot. As shown in the patent to Black, when the punch is inserted intothe cavity of the die, the distance between the punch and the innersurfaces of the die cavity is always greater than the thickness of themetal sheet material being punched. Thus, the teeth are produced insideof the cavity without actually contacting or being forced against thecavity walls.

SUMMARY OF THE PRESENT INVENTION

An object of the present invention is to provide an improved connectorplate capable of being either pressed or rolled into the members to beinterconnected.

Another object of the present invention is to provide an improvedstructural joint formed by two wooden members abutted together andinterconnected by an improved connector plate.

A further objective of the present invention is to provide an improvedconnector plate capable of more easily penetrating the wooden members tobe connected while suffering little or no bending action of the teeth ofthe connector plate as it is rolled into the wooden members.

Another object of the present invention is to provide a connector platehaving a plurality of teeth with each tooth having a knife edge portionwith a sharp edge for facilitating entry of the teeth into the woodenmembers so as to limit the tendency for collapsing of the wood.

A still further object of the present invention is to provide animproved connector plate capable of providing a resistance againstrotation of the wooden members interconnected by the connector plate.

Still another object of the present invention is to provide a connectorplate with a knife edge portion having a cross-sectional angle ofpreferably less than 15°.

A still further object of the present invention is to provide aconnector plate having a knife edge portion produced by a metal formingprocess so as to be thinner than the remainder of the tooth and so as tobe harder than the material from which the tooth is struck.

Still another object of the present invention is to provide an improvedconnector plate having at least nine teeth struck from the plate persquare inch and having a net section across the length of the plate with63% of the steel remaining intact and a net section across the width ofthe plate with 33% of the steel remaining intact.

The above-noted objectives are achieved by the production andutilization of a connector plate made in accordance with the presentinvention. The connector plate is produced from a metal plate by an aircutting and metal forming process. The plate is provided with aplurality of pairs of elongated teeth that are struck from the plate soas to project in a direction substantially perpendicular to the plate.Each of the pairs of teeth is struck from the plate so as to leave acorresponding longitudinally extending slot between the teeth of thepair. Each of the teeth has a knife edge portion that extends from theplate. The knife edge portion of each tooth is thinner than theremaining portion of the tooth and has a sharp edge with a crosssectional angle of less than 20° and preferably less than 15°, forfacilitating penetration of each of the teeth into the members to whichthe connector plate is to be attached.

The knife edge portions of the teeth of each pair substantially face theother tooth of the pair. Each of the teeth of each pair aresubstantially reverse mirror images so that their knife edge portionsextend in the same direction around the slot. A first group of pairs ofteeth of the connector plate have their knife edges extending in onedirection around the slot while the other pairs of the teeth of theconnector plate have their knife edges extending in the oppositedirection around the slot.

Since each of the knife edge portions of the teeth is formed by a metalforming process, such portions are harder than the metal from which thetooth is made. The increase in hardness of the tooth along with thesharpness of the knife edge portion improves the capability of the toothto slice through the wood and to penetrate the wood as the connectorplate is rolled into the wooden members. Ideally, the knife edge portionshould have a sharp edge with a cross sectional angle of between 8° and12°. In addition, the knife edge portion from the tip of the toothextends along an arcuate path toward the metal plate. Such an arcuatepath also helps to facilitate penetration of the tooth into the wood.

During the metal forming process of producing the teeth, the section ofthe tooth forming the knife edge is wiped against the inner wall of thecavity by an end wall of the punch. This wiping, or metal forming,action increases the width of this portion of the tooth so that theoverall width of the tooth increases from approximately 0.094 inches to0.125 inches. Simultaneously, the length of the tooth is also increasedby approximately 0.025 inches due to the wiping, or metal formingaction. Thus as a result of the metal forming process, the size andshape of the tooth along with its thickness are changed. In addition,however, due to the construction of the punch and the correspondingformation of the cavity of the die, the teeth are forced to besubstantially aligned with the corresponding slots. The pointed tip ofeach tooth substantially lies along the longitudinal center line of itscorresponding slot with the only distance between alignment beingrelatively minor; this distance is referred to as the point offset.

The inner surface of each tooth is approximately "V-shaped". The outersurface of each tooth, however, is approximately rounded in itscross-sectional shape. While the knife edge of each tooth follows anarcuate path extending from the tip towards the base of the tooth, theother edge of the tooth is angular in shape. Preferably, there should beat least 9 teeth per square inch and ideally, there are approximately9.5 teeth per square inch.

In producing the connector plates of the present invention, the sheetmetal material from which the plate is to be formed is incrementallypassed between a series of punches and corresponding dies. The punchesand dies are arranged so that each punch will strike the metal plate andpass through the plate so as to extend into a cavity of a correspondingdie. When the punch extends into the cavity of the die, a substantialportion of the space between the lateral side edges of each punch andcorresponding die is less than the thickness of the sheet metal plate.Thus, as the punch enters into the cavity of the die metal formingoccurs whereby the teeth are reshaped by wiping the metal between theside walls of the punch and the die cavity. In this manner, the knifeedge portion of each tooth is formed with a thickness less than the restof the tooth and having a sharp edge with a cross-sectional angle ofideally between 8° and 12°.

While the teeth will initially be twisted when the punch begins to enterthe die cavity, similar to the twists that exist in the Hydro-Air plate,as the punch is fully inserted into the die cavity, each tooth will befored into a position vertically aligned with the slot and rotated sothat the knife edge portion of each tooth extends along a longitudinalside of the slot by a distance greater than the other side of the sametooth. The metal forming operation for producing the knife edge portionof each tooth also increases the hardness of such portion and increasesthe width of the tooth as compared to the width when first cut from theplate.

The punch press for punching the connector plates includes upper andlower relatively movable die shoes such as shown in U.S. Pat. No.3,314,271 to Otis. A punch is secured to one of the shoes and acorresponding die for receiving the punch is secured to the other shoe.When the metal stock material passes through the press between theshoes, the punch strikes the metal stock material, passes through thematerial and passes into a cavity of the die which serves to receive thepunch. As the punch cuts through the metal stock material, it cuts apair of teeth of the connector leaving a slot between the teeth. Thepunch and the cavity of the die are constructed so that when the punchextends into the cavity a portion of the space at the lateral end wallsis less than the thickness of the metal stock material thereby causingthe teeth to be shaped between the punch and the die by a metal formingaction. Such metal forming action occurs when the metal material isextruded between the punch and interior walls of the die cavity; thisserves to form the knife edge portions of the teeth and also widens andelongates the teeth.

When the punch is inserted into the cavity of the die, a pair ofcorresponding opposite corners of both the punch and the cavity eachform an angle therebetween of preferably less than 15° and are spacedfrom each other by a distance less than the thickness of the metal stockmaterial to be punched. Thus, as each tooth is punched and shaped by themetal forming action so as to form the knife edge portion, this portionshould be provided with a sharp edge having an angle of less than 15°.Ideally, the sharp edge should have an angle of between 8° and 12° andaccordingly the angle between the punch and cavity at the aforementionedopposite corners should be between 8° and 12°.

The punch and the cavity of the die each have 6 side walls around itscircumference. The cavity has two longitudinal parallel side walls, twopartial lateral parallel side walls, which are perpendicular to thelongitudinal side walls, and two slanted side walls, which are locatedat opposite corners of the die. Each of the slanted side walls of thecavity at one end is attached to the adjacent longitudinal side wall ofthe cavity so as to form an angle with such wall of between 30° and 40°.The punch has two longitudinal parallel side walls, two partial lateralside walls, which are perpendicular to the longitudinal side walls, andtwo slanted side walls, which are located at opposite corners of thepunch. Each of the slanted side walls is attached to the adjacentlongitudinal side wall of the punch and forms an angle with suchlongitudinal side wall of between 40° and 50°. The face surface of thepunch that initially contacts and cuts the metal stock material has aprimary cutting edge at its upper end. This primary cutting edge extendsalong a diagonal between the two longitudinal side walls of the punchand forms an angle with a longitudinally extending line along each ofthe longitudinal side walls of between 30° and 45°. The face surface ofthe punch also has two metal shaping surfaces. Each of the metal shapingsurfaces extends from the cutting edge to a respective one of thelongitudinal side walls. Each of the metal shaping surfaces isdimensioned for causing rotation of the corresponding tooth so that theknife edge portion of such tooth extends further along the slot betweenthe pair of teeth than the other side of the same tooth whilesimultaneously causing such tooth to project from the metal stockmaterial free of any twist. Thus, each tooth stands in a substantiallyvertical manner free of the type of twist present in the Hydro-Airplates such as shown in FIG. 8. Each of the metal shaping surfaces hasone side extending from one of the longitudinal side walls of the punchat the end of the cutting edge across the face surface of the punch tothe opposite longitudinal side wall with such side of the metal shapingsurface forming an angle of between 52° and 58° with a horizontal planelying along the cutting edge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom plan view of a connector plate in accordance with thepresent invention with the teeth shown extending up from the plate.

FIG. 2 is a perspective view of a portion of the connector plate shownin FIG. 1.

FIG. 3 is a cross-sectional view of a pair of teeth of the connectorplate illustrated in FIG. 1.

FIG. 4 is a side elevational view along lines A--A of FIG. 3.

FIG. 5 is a bottom plan view of a punch within a die cavity, with thepunch and die illustrated being an A type punch and die.

FIG. 6 is a bottom plan view similar to FIG. 5 except that a B typepunch and die are illustrated.

FIG. 7 is a side elevational view of a portion of the punch illustratedin FIG. 5 taken along lines B--B.

FIG. 8 is a perspective view of a portion of a prior art connectorplate.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A connector plate for connecting together wooden members in theconstruction of a structural joint has a plurality of pairs of teethstruck therefrom such as shown in FIG. 1. Each pair of teeth, such asteeth 4 and 6 are struck so as to form a slot 8 therebetween. Connectorplate 2 has a plurality of rows of such pairs of teeth such as rows R1and R2. The rows of teeth extend longitudinally along the connectorplate. Typically, the connector plate is elongated along itslongitudinal direction. The adjacent rows of teeth are offset from eachother by a distance d, which is referred to as the stagger distance. Inaddition, the space between each pair of teeth along each row should beapproximately equivalent to one half of the length of the slot.

Each tooth is provided with a knife edge portion, such as portion 10 oftooth 4 and portion 12 of tooth 6, as shown in FIG. 2. Each knife edgeportion has a sharp edge 14 with a cross-sectional angle of ideally 8°to 12°. The sharp edge 14 of each of the knife edge portions has anarcuate shape extending from the tip 16 of the tooth towards the metalstock material 1.

The cross-sectional shape of each of the teeth is more clearly shown inFIG. 3. As shown, tooth 4 has a knife edge portion 10 with sharp edge14. Each of the sharp edges has an arcuate shape such as shown on knifeedge portion 12. The outer surface of each tooth is rounded such asshown by outer surface 22. The inner surface of the tooth isapproximately V-shaped such as shown by inner surface 18.

Viewing the tooth from a direction facing the outer surface, such asshown in FIG. 4, it can be seen that the tooth extends in a directionsubstantially perpendicular to the metal stock material 1 forming theconnector plate. Each tooth, therefore, is substantially aligned withthe slot and is not leaning in either direction such as shown in theprior art connector illustrated in FIG. 8. The tip 16 of tooth 4 issubstantially aligned along the longitudinal center of the slot, onlybeing offset by a minor distance p referred to as the point offset.Sharp edge 14 of knife edge portion 10 has an arcuate shape. The otherside of the tooth has an angular shape 20 such as shown in FIG. 4.

A first group of the pairs of teeth will have their knife edgesextending in a first direction around the slot such as shown in FIG. 3.The remaining pairs of teeth, however, have their knife edges extendingin the opposite direction around the slot. In this manner, while thefirst group of teeth will provide a lateral resistance againstrotational forces in one direction, the second group of pairs of teethwill provide resistance against rotational forces in the oppositedirection. The first group of teeth are formed by a type A punch and dieassembly while the second group of pairs of teeth are formed by a type Bpunch and die assembly. The type B punch and die assembly is merely areversed image of the type A punch and die assembly. The teeth of eachpair of teeth ideally have the same shape and are reverse mirror imagesof each other.

In accordance with the preferred embodiment of the present invention,the connector plate can be made of 20 gauge metal or alternatively 18guage. The length L of the slot, which is shown in FIG. 3, isapproximately 0.442 inches. The width W of the slot shown in FIG. 3 isapproximately 0.094 inches. The height H of each tooth is approximately0.312 inches and the width of each tooth is approximately 0.125 inches.The width of the tooth upon completion of the metal forming process islarger than the width of the slot. The included angle α of the sharpedge of the knife edge portion is approximately 10°.

The punch and dies for fomring the teeth of the connector plate of thepresent invention are illustrated in FIGS. 5 through 7. As previouslyindicated FIG. 5 shows the first punch and die arrangement, which can bereferred to as the type A embodiment and FIG. 6 shows the reverse punchand die arrangement which can be referred to as the type B embodiment.The type A and type B embodiments are alternately arranged along alateral row with each of the adjacent punch and die assemblies beingoffset by the stagger distance d so as to cause the correspondingstagger distance d between the adjacent pairs of teeth of the connectorplates such as shown in FIG. 1.

Die 26 has a cavity 28 for receiving punch 24. The cavity of die 26 hastwo longitudinal parallel side walls, two partial lateral side walls andtwo slanted side walls, such as shown in FIG. 5. The slanted side wallsare arranged at opposite corners of the die cavity and form an angle Awith the longitudinal side wall of between 30° and 40°. The lateral sidewalls of the die cavity are spaced by a distance L1. The distancebetween the lateral side walls of the die cavity is w1. The lateralparallel side walls have a width w2. In the preferred embodiment, L1 is0.518 inches, w1 is 0.104 inches, w2 is 0.064 inches and angle A is 35°.

Punch 24 is also six sided and has two longitudinal parallel side walls,two partial lateral parallel side walls and two slanted side walls. Theslanted side walls are connected to the longitudinal walls of the punchand form an angle B of between 40° and 50°. The distance between thelateral side walls of the punch is L2. The width of the entire punch isw3 and the width of the lateral side wall is w4. In accordance with thepreferred embodiment, L2 is 0.442 inches, w3 is 0.094 inches, w4 is0.057 inches and angle B is 45°. The thickness of the 20 gauge metalstock material is approximately 0.0396 inches. Thus, a metal formingoperation which causes shaping and thinning of the metal takes place inthe area between the slanted side walls of the punch and cavity so as toform the knife edge portion with this portion having a cross-sectionalangle of 10° in accordance with the preferred embodiment.

The angles, lengths and widths of the type B embodiment as shown in FIG.6 would be similar to those in the type A embodiment of FIG. 5. In thetype B embodiment there is a punch 30 that enters cavity 34 of die 32.

Turning now to the face surface of punch 24 with reference to FIGS. 5and 7, it is seen that the punch has a cutting surface 36 at itsuppermost end. Cutting edge 36 is the cutting edge that initiallystrikes the stock metal plate for creating a slit that serves to producethe two teeth. Cutting edge 36 forms angles C and D with thelongitudinal side walls of the punch. Angles C and D should be the sameand the angles should be between 30° and 45°. Extending down fromcutting edge 36 are two metal shaping surfaces 25. The sides 38 and 40of the two metal shaping surfaces are oriented at angles E and F,respectively, with respect to a horizontal line extending along cuttingedge 36. Angles E and F should be identical and should be between 52°and 58°. In accordance with the preferred embodiment of the presentinvention, angles C and D are 35° and angles E and F are 55°.

During the punching operation, after cutting edge 36 pierces a metalstock plate for cutting the two pointed ends of the teeth, punch 24continues to be inserted into the cavity. As punch 24 moves in apiercing direction into the cavity, a metal forming operation occursbetween the slanted side walls of the punch and the die cavity. Inaddition to this metal forming operation, metal shaping surfaces 25rotates the teeth so that they extend from metal stock material 1 in asubstantially vertical direction free of any twist. In this regard, ifthe angle between the upper edge of the metal shaping surface and thehorizontal line along cutting edge 36 of the punch is too large thenthis will decrease the capability of the punch for rotating the teeth sothat the forward edge of the knife edge portion extends further forwardalong the slot than the other side of the tooth. If the angle of thisedge of the metal shaping surface is too small then the metal shapingsurface will be unable to remove the twist from the tooth and a twistsuch as shown in the prior art connector plate of FIG. 8 will occur.

In accordance with the preferred embodiment of the present invention,each pair of teeth extending along a longitudinal row of the connectorplate is spaced from the next pair of teeth by a distance ofapproximately 0.339 inches. The lateral distance between each pair ofteeth in accordance with the preferred embodiment is approximately 0.176inches. The length of each slot in accordance with the preferredembodiment is approximately 0.442 inches and the width of each slot inaccordance with the preferred embodiment is approximately 0.094 inches.The stagger distance between the pairs of teeth in adjacent rows isapproximately 0.089 inches. In any net section extending lengthwisealong the connector plate, ideally approximately 63% of the steelremains, i.e., the percentage of steel in which no slots have beenformed. The percentage of steel remaining in a net section across thewidth of the connector plate is approximately 33%. The number of nailscut from the plate is preferably 9.5 nails per square inch.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresent embodiments are presented merely as illustrated and notrestrictive, with the scope of the invention being indicated by theattached claims rather than the foregoing description. All changes whichcome within the meaning and range of equivalency of the claims aretherefore intended to be embraced therein.

The embodiment of the invention in which an exclusive property orprivilege is claimed is defined as follows:
 1. A structural joint forbearing a structural load comprising: a pair of wooden members fastenedtogether by at least one metal connector plate, said connector platehaving: a plurality of pairs of elongated teeth struck from said plateso as to project in a direction substantially perpendicular to saidplate; said teeth being struck in pairs so as to leave a plurality oflongitudinally extending slots with each of said pairs of teeth beingassociated with one of said slots; each of said teeth having a pointedtip; each of said teeth having a knife edge portion extending from saidplate, said knife edge portion of each said tooth having across-sectional thickness thinner than the remaining portion of saidtooth and having a sharp edge with a cross-sectional angle of less than20° and said sharp edge of each said knife portion extending from saidpointed tip of each of the respective said teeth along a continuoussubstantially arcuate path to said plate for facilitating penetration ofeach of said teeth into the respective wooden member to which saidconnector plate is attached; said knife edge portion of said teeth ofsaid pairs of teeth lying along opposite longitudinal sides of thecorresponding said slot; a first group of said teeth of said pairs ofteeth being oriented so that their said knife edge portions extend alongthe corresponding said slots in one direction; and a second group ofsaid teeth of said pairs of teeth being oriented so that their knifeedge portions extend along the corresponding said slots in the oppositedirection.
 2. A structural joint according to claim 1 wherein all ofsaid teeth project from the same side of said metal plate.
 3. Astructural joint according to claim 1 wherein said metal plate has atleast 9 teeth per square inch.
 4. A structural joint according to claim1 wherein said pointed tip of each of said teeth lies substantiallyalong the longitudinal center line of the corresponding said slot.
 5. Astructural joint according to claim 1 wherein each of said teeth issubstantially aligned with its corresponding said slot.
 6. A structuraljoint for bearing a structural load comprising: a pair of wooden membersfastened together by two metal connector plates, each of said connectorplates having: a plurality of pairs of elongated teeth struck from saidplate so as to project in a direction substantially perpendicular tosaid plate; said teeth being struck in pairs so as to leave a pluralityof longitudinally extending slots with each of said pairs of teeth beingassociated with one of said slots; each of said teeth having a pointedtip; each of said teeth having a knife edge portion extending from saidplate, said knife edge portion of each said tooth having across-sectional thickness thinner than the remaining portion of saidtooth and having a sharp edge with a cross-sectional angle of less than20° and said sharp edge of each said knife portion extending from saidpointed tip of each of the respective said teeth along a continuoussubstantially arcuate path to said plate for facilitating penetration ofeach of said teeth into the respective wooden member to which saidconnector plate is attached; said knife edge portion of said teeth ofeach of said pairs of teeth lying along opposite longitudinal sides ofthe corresponding said slot; a first group of said teeth of said pairsof teeth being oriented so that their said knife edge portions extendalong the corresponding said slots in one direction; and a second groupof said teeth of said pairs of teeth being oriented so that their knifeedge portions extend along the corresponding said slots in the oppositedirection.
 7. A structural joint according to claim 6 wherein all ofsaid teeth project from the same side of said metal plate.
 8. Astructural joint according to claim 6 wherein said metal plate has atleast 9 teeth per square inch.
 9. A structural joint according to claim6 wherein said pointed tip of each of said teeth lies substantiallyalong the longitudinal center line of the corresponding said slot.
 10. Astructural joint according to claim 6 wherein each of said teeth issubstantially aligned with its corresponding said slot.